Movement across cells

• The rate of diffusion depends on temperature, surface area, and concentration gradient.
• Diffusion is the movement of particles from an area of high concentration to low concentration until equilibrium is reached.
• The concentration gradient, or the difference in concentration between two areas, affects the rate of diffusion.
• Passive transport does not require energy input and moves molecules with or down their concentration gradients.
• Active transport requires energy input and moves molecules against their concentration gradients.
• an organism needs a system of transport so that nutrients and waste products can be transportedt to the location they need to go
• There are two types of transport. Passive transport and active transport
• The two types of passive transport are diffusion and osmosis
• A concentration gradient is the difference in concentrtions between two regions
• Passive transport uses no energy and moves from a high conc. to a low conc.
• Active transport needs energy and moves from a low to a high conc going against the concentration gradient
• Diffusion takes place during the photosynthesis process when CO2 is expelled out and O2 is taken in
• Diffusion takes place in the alveoli of our lungs where oxygen diffuses into our bloodstream and CO2 is taken out.
• Diffusion is seen also in the digestive system with vili
• Diffusion occurs in the ameoba, an animal cell.
• The higher the temperature, te faster the rate of diffusion.
• Temperature affects the rate of diffusion since it increases kinetic energy of the atoms thus causing them to move at high speeds.
• The larger the distance, the slower the diffusion.
• The larger the size of molecules or ions, the slower the rate of diffusion
• The surface area to volume ratio can be caluclated by

  1. Calculating the Surface area
  2. Calculating the Volume
  3. Divide the Surface area with the Volume
• Osmosis is the movement of water from a high water concentration to a low water concentration through a semi-permeable membrane.
• In a semi-permeable membrane, water can pass but other big particle substances cannot such as salt or sugar.
• High water concentration is also referred to as a high water potential
• A high water potentional results to a dilute solution.
• A low water potentional is known to be referred to as concentrated
• Osmosis is a natural process whilst reverse osmosis is not. This means that a lot of energy and pressure is needed
• In reverse osmosis, salt water is pushed against a semipermable membrane. Water passes through but the salt doesn't. Here water moves from a high conc to a low conc
• An isotonic solution is one which has the same concentration as the inside of the cell.
• A solution that is more concentrated that inside the cell is called a hypertonic solution.
• A solution that is more dilute that inside of the cell is a hypotonic solution.
• In hypotonic solutions, water moves in the cell by osmosis.
• In Isotonic solutions, water moves in and out of the cell
• In concentrated solutions, water moves out by osmosis
• In a hypotonic solution, the cell bursts
• In an isotonic solution, the cell remains normal
• Is a hypertonic solution, the cell shrivels/shrinks
• A person should not drink salt water since the blood would have a high concentration of salt in it (Hypertonic soution). Water from the cells would enter an leave the cells to shrink
• Our body converts glucose into glycogen and fat since glucose is soluble in water. Apart from this, glucose in cells would cause osmosis to occur thus letting water in the cell and making the cell burst
• In plants, osmosis can cause a cell to become flaccid, turgid or plasmolyzed
• A plant cell placed in a hypertonic solution will cause it to become plasmolyzed.